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Location: Essexville, MI./Saginaw Bay. | Sent this question to my DNR buddy for his ideas on the subject.
Q: For some reason this year many of us are catching a lot of smaller females (19 to 21 inches) on Saginaw Bay that are already carrying mature eggs, yet are not bulging or showing any signs of this. They all seem healthy enough, but showing few outward signs of being mature, ready to spawn, egg carrying females. I myself caught 4 the other day that were 19 to 21 inches and all plump and basically the same body size. I thought all 4 were males, but to my surprise 3 were mature (near spawn) females. Is there any other way for layman like us to determine what sex a walleye is?
A: Dan:
I ran a summary of our survey data to see if maybe there were some recent trends for earlier maturity in our female walleye, but I detected none. I think what you are seeing is not earlier maturing walleyes, just lots of females stemming from the record 2007 year class. Yes 2007 is our new record based on our catch rate in our survey nets as yearlings. They are three years old this spring and while thats a bit early to see mature females, we certainly see some that early and I think that's what you are catching. Hard to say for sure without some scales to age them by. Its possible that as growth rates have slowed some, that they are opting to produce eggs at an earleir age but the data doesn't really say that so far. There is some evidence that these young females produce more viable eggs than old fish (percentage wise). If so, these will make some good spawners this spring.
Did you hear that we had a new record catch of young-of-the-year walleyes last fall in our annual trawl survey. It was like another 30% more than the old record of 2003. This is at the YOY stage so we'll have to wait and see if they survive well enough to lock in a record year class at the yearling stage (when we mostly judge year class strength), but it still is incredible and bodes very well for the ongoing abundance of walleye in the bay. I'm really curious to see how the fishery shapes up this spring and early summer.
In answer to your question, no there is no external way to sex a walleye unless they are ripe and then gently squeezing the belly will emit gametes. If they don't (during the spawning period) then we regard them as either immature fish or "green females" (mature females whose eggs have not yet ripened sufficiently to be free flowing). Generally the mature males are easy to recognize as they are emitting milt over a long span of time in the spawning period. There are a few species that some believe you can sex the fish by virtue of its morphology (usually the shape of the vent) but I have never seen that in walleye or heard of anyone saying that they can tell. |
Why so many small/mature females this year.